Just some reports using the keyword "sold"
It happens, usually on week-ends (alcoholists).
Of course if you are sure to never do any kind of mistakes you won't find any purposes on using the system, but if you have for example a sword, that you never trade with anyone, you never change bonus because they are perfect and you use it always either to farm or to pvp, why taking the risk of losing it for a dumb mistake?
Never but never blame a beer! beer is our friend! xD i didnt know it happend so much o,o